Superimposed emery-wheel and grindstone.



D. HALL. SUPEBIMPOSED EMERY WHEEL AND GRINDSTONE.

APPLICATION FILED MAR.7, 1913.

Patented Mar. 2, 1915.

INVENTOR A TTORNE Y THE NORRIS PETERS CO.. PHOTG-LITHO.. WASHINGTON. u.C.

DAVID HALL, OF WILKINSBURG, PENNSYLVANIA.

SUPERIMPOSED EMERY-WHEEL AND GRINDSTONE.

Application filed March 7, 1913.

cavities of cut and using the larger stone as a fly wheel for thesmaller stone. Tool rests 20 and 21 are shown.

Further purposes of my invention will appear in the specification andclaim hereof.

I have preferred to illustrate my invention by one form thereof which ispractical, inexpensixe and eiiicient and which at the same time wellillustrates the principles of my invention.

Figure 1 is a side elevation of the preferred form of my invention. Fig.2 is a rear elevation of the structure seen in Fig. 1.

Similar numerals of reference indicate like parts in the figures of thedrawing.

1 represents uprights or supports forming part of a frame having topbars 2 braced to the uprights, as at 3, and supporting a pillow or othersuitable bearing 4, within which the shaft 5 is rotated by arms 6, 7,through rods 8 and treadles 9, pivoted at 10.

The shaft 5 carries the main stone 11, preferably a grind stone, towhich I attach a pulley wheel 12, as by studs 18. A much smaller stone14;, preferably of emery or .carborundum is mounted above the main stoneupon a shaft 15 parallel to the shaft 5 and is supported by arms 16 at aconvenient distance from the seat 17 occupied by the workman. Forconvenience in reference and claiming, I shall hereafter use emery as ageneral term to refer to materials of like general character, whethernatural or artificial. I drive the auxiliary stone 1 1 from the pulleyupon the main stone, and a much smaller pulley 18, upon the shaft 15,using any desired belt or chain drive, here represented by a rope 19. I

Specification of Letters Patent.

Patented Mar. 2, 1915.

Serial No. 752,541.

prefer to place the center of the smaller stone directly above thecenter of the larger one, though its position about the axis of thelower stone, whether nearer to or farther from the seat for the operatorwill not ordinarily be material.

I intend the upper stone for rougher grinding and operate it at a niuchhigher speed than the speed of the lower stone, even ten times the speedbeing desirable for some uses with a small auxiliary, the speeddesirable varying with the size but always much greater than that of themain stone, in order that I may effect the above purpose and at the sametime give a greater concavity to the tools or other parts thus roughground, so that the rake or clearance of machine tools, etc., may begiven to advantage during the rough grinding and the larger and finerstone need be used for the finish only.

he direct connection which I have shown between the two stones enablesme to obtain to the fullest degree a balance wheel effect of the lowerstone upon the upper stone, so that with a small upper stone I am ableto get regular and forcible rotation from treadle operation.

It will be evident that the characters as well as the sizes of thestones, may be modified to suit the needs of different workmen, providedthere be a considerable difierence in their sizes and the character oftheir cutting faces.

It will be evident that reference to belt connection herein may properlyinclude such connection, whether by link, chain or other belting. It isevident that tool rests may be removable or adjustable, as desired.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

In a device of the character stated, a pair of abrasive stones ofdifferent surface characters having substantially parallel aXes and onemuch larger than the other and adapted to act as a fly wheel for theother, operative connection between the stones, supports for the stonesand means for driving the larger stone.

DAVID HALL. Vvitnesses:

F. G. MONROE, R. F. MCKINNEY.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents,

Washington, D. C.

